Complete combustion of methane and higher order hydrocarbons is difficult to achieve under fuel-rich conditions in microchannel reactors with relatively short contact times. The combustion is incomplete and this leads to undesirable levels of carbon monoxide and carbon deposits. The problem therefore is to find a way in which to conduct a complete combustion reaction in a microchannel reactor. This invention provides a solution to this problem.
Partial oxidation reactions typically involve reacting a hydrocarbon with oxygen in the presence of a catalyst to form hydrogen and carbon monoxide. Examples include the conversion of methane to hydrogen and carbon monoxide. A problem with these reactions is that they are exothermic and are typically conducted in fixed bed reactors where hot spots tend to form. The formation of these hot spots increases the tendency of the catalyst to deactivate. This invention provides a solution to this problem.
This invention relates to a process wherein a partial oxidation reaction or a partial oxidation reaction coupled with combustion reaction is conducted in a microchannel reactor wherein the tendency to form hot spots is reduced and selectivity to the desired product is enhanced. Reductions in these hot spots with the inventive process is believed to be due at least in part to the fact that the microchannel reactor provides enhanced heat transfer characteristics and more precise control of residence times. In one embodiment, a novel, stable and highly active partial oxidation catalyst is used in the inventive process.
With the inventive process it is possible to obtain relatively high heat and mass transfer rates and shorter contact times as compared to prior art processes wherein microchannel reactors are not used. This provides for more precise temperature control as compared to such prior art. This, in turn, leads to an increase in catalyst durability and a reduction in the formation of undesired by-products. With this process, it is possible to obtain relatively high levels of conversion of the hydrocarbon reactant and high levels of selectivity to the desired product as compared to such prior art.